Longitude: W 117°53'25"
Length: 795.8m
Number of Bench marks: 22
Number of Surveys to 2000: 15
Date of Initial Survey: 25 September 1974
Date of Latest Survey: 23 July 1996
Trespass Permission: None required; however, it is best to reach the array by a road along
the east side of Duravan Ranch rather than through the ranch itself. Beware of desert tortoises and rattlesnakes.
Directions:
From Mojave, proceed northeast on Hwy 14 about 4 miles to California City Blvd.; thence east about 6.5 miles to California City; thence north 11.1 miles on Neuralia Road to Munsey Road; thence east about 5.5 miles to entrance Duravan Ranch. The leveling a rray is in the open desert south of the Duravan Ranch property line, and it follows some of the old subdivision roads.
Comments:
This W-shaped array was established in 1974 across one of the main active scarps related to subsidence caused by ground water withdrawal on the floor of Fremont Valley, Mojave Desert. Wholesale irrigation of Fremont Valley ceased in the early 1980s. Bench marks established in 1974 were abandoned in August 1978 because they had been built down the center line of a dirt road. New bench marks corresponding to the old ones were established along the edge of the road on 22 August 1978. Comparative surveys of the two sets of bench marks, old and new, were done on 23 and 24 August 1978, respectively. The old bench marks have not been resurveyed subsequently.
Results:
From 1974 to 1996 vertical displacement across the fault exceeded 600 mm and proceeded episodically at an annual rate of 38 mm/yr from 1974 to 1983. It has slowed considerably, from 1983 to 1996, because much of the irrigation and ground water withdrawal has ceased.
